Seed size and chloroplast DNA of modern and ancient seeds explain the establishment of Japanese cultivated melon (Cucumis melo L.) by introduction and selection

摘要: Melon is a fruit/vegetable that has been grown in Japan for at least 2000 years. To obtain better understanding of melon crop evolution this island country, we measured the seed size and determined cytoplasmic genotype 135 modern accessions 12 populations ancient remains from archaeological sites 2000-year period Japan. Based on differences length, Shikata site (Okayama Prefecture, Japan) consisted types corresponding to those East South Asian melon. Although several seeds were found around site, only Agrestis-type seeds, <6.1 mm 1 CE. Intra-population length variation was higher 1050 CE than 1530–1680 Ancient DNA analysed SNPs chloroplast genome. These revealed cytoplasm type heterogeneous Ia Ib prior ca. 1600 CE, thereafter becoming homogenous by genetic erosion Ib, which absent endemic Japanese accessions. The decrease both together with historical records indicates artificial selection melons desired fruit traits intensified past 1000 years.